Sailboards are generally constructed of a board of lightweight synthetic plastic material to which is pivotally attached a mast which supports a boom and sail. The mast, boom and sail are controllable by the user to convert wind to motive power for the sailboard.
The board includes a fin which is positioned on the lower, rearward, central underside of the board extending into the water. This fin is generally referred to as a skeg and is usually fixed in size, shape and position. The skeg provides hydrodynamic forces which combine with the aerodynamic forces on the sail to provide motive power to the board. Such skegs are used with all sailboards.
For boards longer than about 101/2 feet, an adjustable area keel positioned generally in the lower center of the boards is also used. Such keels are known as centerboards or daggerboards. A typical centerboard is about two feet in span and about 6 inches in chord, while a typical skeg is about eleven inches in span and four inches in chord. U.S. Reissue Pat. No. 31,167 illustrates a typical sailboard which uses both a centerboard and skeg.
Centerboards also provide hydrodynamic forces which combine with the forces generated by the sail to produce a net force which is in the direction of motion of the sailboard. When a centerboard is not used, however, the skeg is the sole means for providing not only directional stability to the sailboard but also lateral resistance.
A profound effect on the performance of the sailboard can be achieved by varying the sizes, shapes and locations of these fins and keels. A fin and/or keel configuration that is fast for one point of sail or wind strength may be slow on another. For example, a sailboard equipped with a centerboard can sail upwind much better than a sailboard which is equipped only with a standard skeg.
The present invention provides an improved skeg construction for optimizing both the upwind and downwind sailing performance of sailboards utilizing same, when such sailboards do not utilize a centerboard.